/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.everrest.core.impl.provider.json;

import java.util.Collections;
import java.util.Iterator;

/**
 * @author <a href="mailto:andrew00x@gmail.com">Andrey Parfonov</a>
 * @version $Id$
 */
public abstract class JsonValue {

    // Set defaults for specific types.
    // It will be overridden.

    /** @return true if value is 'object', false otherwise. Should be overridden. */
    public boolean isObject() {
        return false;
    }

    /** @return true if value is 'array', false otherwise. Should be overridden. */
    public boolean isArray() {
        return false;
    }

    /** @return true if value is 'numeric', false otherwise. Should be overridden. */
    public boolean isNumeric() {
        return false;
    }

    /** @return true if value is 'long', false otherwise. Should be overridden. */
    public boolean isLong() {
        return false;
    }

    /** @return true if value is 'double', false otherwise. Should be overridden. */
    public boolean isDouble() {
        return false;
    }

    /** @return true if value is 'String', false otherwise. Should be overridden. */
    public boolean isString() {
        return false;
    }

    /** @return true if value is 'boolean', false otherwise. Should be overridden. */
    public boolean isBoolean() {
        return false;
    }

    /** @return true if value is 'null', false otherwise. Should be overridden. */
    public boolean isNull() {
        return false;
    }

    /**
     * Add child value. This method must be used if isArray() gives true.
     *
     * @param child
     *         the child value.
     */
    public void addElement(JsonValue child) {
        throw new UnsupportedOperationException("This type of JsonValue can't have child.");
    }

    /**
     * Add child value. This method must be used if isObject() gives true.
     *
     * @param key
     *         the key.
     * @param child
     *         the child value.
     */
    public void addElement(String key, JsonValue child) {
        throw new UnsupportedOperationException("This type of JsonValue can't have child.");
    }

    /**
     * Get all element of this value.
     *
     * @return Iterator.
     */
    public Iterator<JsonValue> getElements() {
        return Collections.<JsonValue>emptyList().iterator();
    }

    /**
     * Get all keys for access values.
     *
     * @return Iterator.
     */
    public Iterator<String> getKeys() {
        return Collections.<String>emptyList().iterator();
    }

    /**
     * Get value by key.
     *
     * @param key
     *         the key.
     * @return JsonValue with specified key.
     */
    public JsonValue getElement(String key) {
        return null;
    }

    /** @return number of child elements. */
    public int size() {
        return 0;
    }

    // Prepared values of know type.
    // It will be overridden.

    /** @return string value. Should be overridden. */
    public String getStringValue() {
        return null;
    }

    /** @return boolean value. Should be overridden. */
    public boolean getBooleanValue() {
        return false;
    }

    /** @return Number value. Should be overridden. */
    public Number getNumberValue() {
        return getIntValue();
    }

    /** @return byte value. Should be overridden. */
    public byte getByteValue() {
        return 0;
    }

    /** @return short Value. Should be overridden. */
    public short getShortValue() {
        return 0;
    }

    /** @return int value. Should be overridden. */
    public int getIntValue() {
        return 0;
    }

    /** @return long value. Should be overridden. */
    public long getLongValue() {
        return 0L;
    }

    /** @return float value. Should be overridden. */
    public float getFloatValue() {
        return 0.0F;
    }

    /** @return double value. Should be overridden. */
    public double getDoubleValue() {
        return 0.0;
    }

    //  must be implemented

    /** {@inheritDoc} */
    @Override
    public abstract String toString();

    /**
     * Write value in given writer.
     *
     * @param writer
     *         Writer.
     * @throws JsonException
     *         if any errors occurs.
     */
    public abstract void writeTo(JsonWriter writer) throws JsonException;

}
